Cryotherapy includes variety of techniques used to treat and/or map tissue, and is commonly used for procedures involving cardiac tissue. Certain types of cryotherapy, such as cryoablation, involves the use of pressurized refrigerant, which is allowed to expand within, and thereby cool tissue adjacent to, the distal portion of the treatment device. The pressurized refrigerant is typically stored in a pressurized tank or cylinder in the console of the system. Although the tank is easily removed and replaced when the refrigerant source runs out, it would be more economical to refill the tank with a new supply of refrigerant. Additionally, the pressurized tanks are considered to be Dangerous Goods, and it would therefore be desirable to reduce the amount of transport, handling, and storage of refrigerant tanks used for cryotherapy procedures.
Many medical facilities, especially hospitals, include a native or in-facility, integrated source of nitrous oxide (N2O), which is commonly used as an anesthetic. Nitrous oxide may also be used as a refrigerant in cryotherapy systems. However, the native nitrous oxide is typically stored at approximately 50 psig, which is considered a low-pressure environment. At this pressure, the nitrous oxide is unsuitable for use in a cryotherapy system and must first be pressurized and safely transferred to the cryotherapy system refrigerant reservoir. The low-pressure refrigerant cannot be used in a cryotherapy system if the refrigerant is simply compressed, since the refrigerant must also be cooled to a temperature suitable for use in the cryotherapy system.
Additionally, current consoles, such as the Gen V CryoConsole (Medtronic, Inc., Minneapolis, Minn.), include an independent refrigeration circuit used to subcool nitrous oxide before it enters a cryotherapy device. However, including the components of the independent refrigeration circuit necessitates a larger and more complex console.
It is therefore desirable to provide a method and system for pressurizing a low-pressure source of refrigerant and safely transferring the pressurized refrigerant to a cryotherapy system. It is further desirable to provide a refrigerant delivery system that includes a pressurization system that provides an interface between a low-pressure refrigerant source and a cryotherapy system. It is further desirable to provide a pressurization system that includes means for subcooling nitrous oxide before it enters a treatment device of the cryotherapy system, as this would allow for the removal of the independent refrigeration circuit from the console of the cryotherapy system.